Subject: [PATCH v26 6/7] arm64: kdump: update a kernel doc

From: [email-masked] (James Morse)
Date: Fri, 16 Sep 2016 17:08:28 +0100

Hi Akashi,

On 07/09/16 05:29, AKASHI Takahiro wrote:
> This patch adds arch specific descriptions about kdump usage on arm64
> to kdump.txt.

> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt

> @@ -249,6 +249,13 @@ Dump-capture kernel config options (Arch Dependent, arm)
>  
>      AUTO_ZRELADDR=y
>  
> +Dump-capture kernel config options (Arch Dependent, arm64)
> +----------------------------------------------------------
> +
> +- Please note that kvm of the dump-capture kernel will not be enabled
> +  on non-VHE systems even if it is configured. This is because the CPU
> +  cannot be reset to EL2 on panic.

Nit:
cannot be -> will not be

We could try to do this, but its more code that could prevent us reaching the
kdump kernel, so we choose not to.

> @@ -370,6 +381,9 @@ For s390x:
>  For arm:
>  	"1 maxcpus=1 reset_devices"
>  
> +For arm64:
> +	"1 maxcpus=1 reset_devices"
> +

'maxcpus=1' is a bit fragile. Since 44dbcc93ab67145 ("arm64: Fix behavior of
maxcpus=N") udev on ubuntu vivid (running on Juno) has taken it upon itself to
bring the secondary cores online, even when booted with 'maxcpus=1'.

Can we change the recomendation to "1 nosmp reset_devices"?

Thanks,

James